1. Field of the Invention
The present invention relates to a liquid crystal display (“LCD”) panel for a multi-display, and more particularly, to an LCD panel for a multi-display that can reduce the size of a seam in a non-image display region.
2. Description of the Related Art
A multi-display realizes a large screen by connecting multiple display panels. In earlier stages of display technology, the large screen was realized by connecting multiple Brown tubes, such as in a large television, as a display. Apparatuses that realize the large screen by connecting flat display panels such as LCDs have been made to meet the requirements for a large screen in small mobile devices such as personal digital assistants (“PDAs”).
FIG. 1 is a perspective view illustrating a multi-display having a conventional LCD panel. As depicted in FIG. 1, the multi-display is realized by connecting unit panels 10. However, a black matrix 11 surrounds edge portions of the unit panel 10. Therefore, when the edges of the unit panels 10 are connected to each other, a seam where images are not seen continuously due to the black matrix 11 is formed, that is, images divided by the two panels look disconnected. Accordingly, to realize a smooth image the width of the edges of the unit panels 10 must be reduced as much as possible to minimize the size of the seam.
The edge portions of the unit panels 10 are surrounded by the black matrix 11 due to the following structural characteristics of the LCD panel. FIG. 2 is a cross-sectional view illustrating an LCD panel for explaining a principle of distortion of an electric field between electrodes 12 of the LCD panel. As depicted in FIG. 2, in the LCD panel, liquid crystals 13 are filled between both electrodes 12 disposed in a sub-pixel unit. The LCD panel has a structure where an arrangement of the liquid crystal molecules 13 changes when a voltage is applied to the electrodes 12 from a power source 14 to selectively transmit light from a light source (not shown).
However, the electric field formed at a central portion has a different electric field than formed at end portions when a voltage is applied between both electrodes 12. That is, the electric field is formed in a straight line between both electrodes 12 at the central portion, but the electric fields formed at the end portions bend outwards. The tendency of the electric field between electrodes in regions except the end portions of the LCD panel is offset by the electrodes 12 disposed to adjacent electrodes 12, but the electric fields at the end portions of the LCD panel where there are no adjacent electrodes 12 curvedly bend outwards (as illustrated by the dotted arrows in FIG. 2). When the electric field bends, the liquid crystals at the region where the electric field bends is arranged abnormally according to the shape of the electric field. Accordingly, the transmittance of light in this region cannot be controlled as desired. A brightness deviation occurs since the brightness of the corresponding region is not displayed as desired.
To address the above-mentioned problem, as depicted in FIG. 3, multiple rows, such as two to three (2-3) rows of dummy electrodes 15 are further disposed on edge regions of the unit panel 10 where the liquid crystal 13 is not filled in order to reduce or effectively prevent the distortion of the electric field. Upper parts of the dummy electrodes 15 are covered by the black matrix 11 since the upper parts of the dummy electrodes 15 are non-image display regions. Because the dummy electrodes 15 reduce or effectively prevent the distortion of the electric field of the electrodes 12 disposed at end portions of the LCD panel that do not contribute to display image, a much lower voltage may be applied to the dummy electrodes 15 than a voltage applied to the electrodes 12. Alternatively, the dummy electrodes 15 may be left floating.
However, when a multi-display is realized using the LCD panel on which connecting edges are surrounded by the black matrix 11, an image discontinuity region is too large. That is, the black matrix 11 blocks the leakage of light at the dummy electrodes 15 which do not contribute to display image. The dummy electrodes 15, like other electrodes 12, have a size equal to a sub-pixel, and are arranged in multiple rows to affect the electrodes 12 disposed at edges of the LCD panel with a low voltage. Therefore, an overall width of the dummy electrodes 15 reaches from 200 microns (μm) to 300 microns (μm). Accordingly, when attaching the widths of the dummy electrodes 15 to form a screen, the image discontinuity region may approximately reach a total of about 400 μm to 600 μm, thereby generating very unstable images.
Accordingly, to realize a smooth multi-display image, the development of an LCD panel that can reduce the seam in the non-display region of the LCD panel is required.